The present invention relates to a heat exchanger for use in a gas quick water heater, boiler, and the like, and more particularly, to a heat exchanger for a gas quick water heater in which water is heated in an indirect heating method for not exposing the exchanger to a high-temperature flame burned in a burner, and in which cold water passes through a plurality of coil-shaped heat exchange tubes to thereby greatly enhance thermal efficiency.
A heat exchanger used in a conventional gas quick water heater, boiler, and the like is installed above a burner, and directly exposed to a high-temperature flame therefrom. In the heat exchanger, a plurality of thermal conduction fins having a high thermal conductivity are attached to the surface of a pipe through which cold water passes, increasing thermal efficiency.
FIG. 1 is a schematic view of a general gas quick water heater. In FIG. 1, cold water supplied through a water supply pipe 1 passes through a heat exchange tube 2, and is then discharged through an outflow pipe 4. Passing through heat exchange tube 2, the cold water is heated directly by a burner 3 installed therebelow. Heat exchange tube 2 is manufactured of copper having an excellent thermal conductivity. Thermal conduction fins 5 are also made of copper, having an excellent thermal conductivity.
Such a directing heating method involves several drawbacks. Since heat exchange tube 2 is exposed to a high-temperature flame above about 750.degree. C., harmful components such as combustion oxides contained in burned gases are adsorbed to thermal conduction fins 5 and heat exchange tube 2. Due to the high-temperature heating, thermal conduction fins 5 and heat exchange tube 2 are corroded to shorten their lives. Since the heat exchanger is expensive, exchanging it causes a lot of cost, increasing the consumer's economic burden. In attaching thermal conduction fins 5 to heat exchange tube 2, there is used lead so as to plug a gap therebetween and thereby prevent rocking therebetween. This increases thermal conductivity rate. As well-known in the art, lead is harmful to create trouble to workers and contaminate environment.